Comparative proteomic analysis of Lactobacillus plantarum for the identification of key proteins in bile tolerance

<p>Abstract</p> <p>Background</p> <p>Lactic acid bacteria are commonly marketed as probiotics based on their putative or proven health-promoting effects. These effects are known to be strain specific but the underlying molecular mechanisms remain poorly understood. Therefore, unravelling the determinants behind probiotic features is of particular interest since it would help select strains that stand the best chance of success in clinical trials. Bile tolerance is one of the most crucial properties as it determines the ability of bacteria to survive in the small intestine, and consequently their capacity to play their functional role as probiotics. In this context, the objective of this study was to investigate the natural protein diversity within the <it>Lactobacillus plantarum </it>species with relation to bile tolerance, using comparative proteomics.</p> <p>Results</p> <p>Bile tolerance properties of nine <it>L. plantarum </it>strains were studied <it>in vitro</it>. Three of them presenting different bile tolerance levels were selected for comparative proteomic analysis: <it>L. plantarum </it>299 V (resistant), <it>L. plantarum </it>LC 804 (intermediate) and <it>L. plantarum </it>LC 56 (sensitive). Qualitative and quantitative differences in proteomes were analyzed using two-dimensional electrophoresis (2-DE), tryptic digestion, liquid chromatography-mass spectrometry analysis and database search for protein identification. Among the proteins correlated with differences in the 2-DE patterns of the bacterial strains, 15 have previously been reported to be involved in bile tolerance processes. The effect of a bile exposure on these patterns was investigated, which led to the identification of six proteins that may be key in the bile salt response and adaptation in <it>L. plantarum</it>: two glutathione reductases involved in protection against oxidative injury caused by bile salts, a cyclopropane-fatty-acyl-phospholipid synthase implicated in maintenance of cell envelope integrity, a bile salt hydrolase, an ABC transporter and a F0F1-ATP synthase which participate in the active removal of bile-related stress factors.</p> <p>Conclusions</p> <p>These results showed that comparative proteomic analysis can help understand the differential bacterial properties of lactobacilli. In the field of probiotic studies, characteristic proteomic profiles can be identified for individual properties that may serve as bacterial biomarkers for the preliminary selection of strains with the best probiotic potential.</p

Proton quantitative nuclear magnetic resonance analysis (1H q-NMR) of various extracts of raw and thermally processed (“Roasted”) coffee (Coffea arabica L.) beans: Influence of the extraction process

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Identification of markers of thermal processing ("roasting") in aqueous extracts of <em>Coffea arabica</em> L. seeds through NMR fingerprinting and chemometrics

International audienceRoasting of Coffea arabica L. seeds gives rise to chemical reactions that produce more than 800 compounds, some being responsible for the desired organoleptic properties for which the beverage called “coffee” is known. In the industry, the “roasting profile,” that is, the times and temperatures applied, is key to influence the composition of roasted coffee beans and the flavour of the beverage made from them. The impact of roasting on the chemical composition of coffee has been the subject of numerous studies, including by nuclear magnetic resonance (NMR) spectroscopy. However, the roasting equipment and profiles applied in these studies are often far from real industrial conditions. In this work, the effects of two critical technological parameters of the roasting process, namely, the “development time” (the period of time after the “first crack,” a characteristic noise due to seed disruption) and the final roasting temperature on coffee extracts, were investigated. Seeds were roasted at pilot scale according to 13 industrial roasting profiles and extracted in D2O. The extracts were analysed by 1H NMR experiments. The NMR spectra were compared using (a) quantitative analysis of main signals by successive orders of magnitude and (b) chemometric tools (principal component analysis, partial least squares and sparse‐orthogonal partial least squares analysis). This allowed to identify compounds, which may serve as markers of roasting and showed that changes in chemical composition can be detected even for slight change in final temperature (~1°C) or in total roasting time (~25 s)

Effects of industrial processing on folate content in green vegetables.

International audienceFolates are described to be sensitive to different physical parameters such as heat, light, pH and leaching. Most studies on folates degradation during processing or cooking treatments were carried out on model solutions or vegetables only with thermal treatments. Our aim was to identify which steps were involved in folates loss in industrial processing chains, and which mechanisms were underlying these losses. For this, the folates contents were monitored along an industrial canning chain of green beans and along an industrial freezing chain of spinach. Folates contents decreased significantly by 25% during the washing step for spinach in the freezing process , and by 30% in the green beans canning process after sterilisation, with 20% of the initial amount being transferred into the covering liquid. The main mechanism involved in folate loss during both canning green beans and freezing spinach was leaching. Limiting the contact between vegetables and water or using steaming seems to be an adequate measure to limit folates losses during processing

Determination of active radical scavenging compounds in polar fruit and vegetable extracts by an on-line HPLC method

Cited by (10) Recommended articles (6)ElsevierLWT - Food Science and TechnologyVolume 62, Issue 1, Part 1, June 2015, Pages 152-159LWT - Food Science and TechnologyDetermination of active radical scavenging compounds in polar fruit and vegetable extracts by an on-line HPLC methodAuthor links open overlay panel, , , , , , ,a Equipe de Chimie Analytique des Molécules Bio-Actives, IPHC-DSA, Université de Strasbourg, CNRS, 74, Route du Rhin, 67400 Illkirch, Franceb Centre Européen d'Etude du Diabète, Université de Strasbourg, DIATECH EA 7294, Boulevard René Leriche, 67200 Strasbourg, Francec Aerial, 250 Rue Laurent Fries, Parc d'innovation, 67412 Illkirch, Franced Interprofession des Fruits et Légumes d'Alsace, 11, Rue Jean Mermoz, 68127 Sainte Croix en Plaine, FranceReceived 12 August 2014, Revised 27 November 2014, Accepted 3 January 2015, Available online 10 January 2015.https://doi.org/10.1016/j.lwt.2015.01.004Get rights and contentAbstractFruit and vegetables are believed to help fight against oxidative stress, given their natural content in radical scavenging compounds. Natural polyphenols neutralize reactive oxygen species by means of electron and hydrogen atom transfers. An HPLC method, hyphenated with a post-column reaction system relying on ABTSradical dot+ bleaching assay was applied in order to quantify the chemical activity of radical scavenging compounds in red cabbage, onion, quince, sweet cherry, strawberry, carrot and tomato. Hyphenated to the ABTSradical dot+ post-column reaction system, this method showed high antioxidant capacity notably in cherry, quince, onion, or red cabbage. Structural analysis of the compounds of interest showed the implication of several cyanidins and caffeoylquinic acids in cherry. Quince and red cabbage were found highly active through the presence of respectively caffeoylquinic acids, and an important content of diverse cyanidins variously glycosylated and acylated. The onion extract revealed a chemical core structure (quercetin) responsible for its antioxidant capacity. Moreover, our results showed that depending on the glycosylation profile of these compounds, their radical scavenging capacity can be very different